Investigating the Effect of Temperature on Rate of Respiration in Yeast

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Investigating the Effect of Temperature on Rate of Respiration in Yeast

Plan

ATP. Glucose is the main energy source, and can be broken down in four different stages: Glycolysis, the link reaction, the Krebs cycle, and oxidative phosphorylation. Yeast is an organism that actively respires aerobically. But it can respire anaerobically, when deprived of oxygen. But anaerobic respiration is not as efficient as aerobic respiration, because oxidative phosphorylation requires a constant supply of oxygen for it to occur; also the link reaction and the Krebs cycle need oxygen. Therefore the link reaction, Krebs cycle and oxidative phosphorylation only work in aerobic conditions, whereas glycolysis can work in anaerobic conditions also. Glycolysis means 'sugar-splitting'. In glycolysis, there is a net gain of 2 ATP molecules. You must start with a hexose sugar, such as glucose. The glucose molecule will undergo phosphorylation. Phosphorylation involves ATP molecules being broken down into ADP and their phosphates are attached to the glucose molecule. The first ATP causes the hexose sugar to be turned into hexose phosphate, and the second ATP molecule makes it hexose bisphosphate. Phosphorylation raises the energy of the glucose, and reduces the activation energy barrier for the pathway. After